Method of handling control plane data in a wireless network

ABSTRACT

The present disclosure relates to a communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology. A method of handling control plane data in a wireless network. The method comprises sending, by a user entity (UE), a non-access stratum (NAS) message along with an indication data to a mobility management (MM) core network entity. The MM core network entity processes the received NAS message and the indication data. The MM core network entity determines status of network congestion upon processing the processed NAS message. Sending, by the MM core network entity, a response to the UE based on at least one of the processed indication data and the determined network congestion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 16/315,286,which is the 371 National Stage of International Application No.PCT/KR2017/007180, filed Jul. 5, 2017, which claims priority to IndianPatent Application No. 201641023071, filed Jul. 5, 2016, Indian PatentApplication No. 201641028365, filed Aug. 19, 2016, Indian PatentApplication No. 201641033734, filed Oct. 3, 2016, and Indian PatentApplication No. 201641023071, filed Jul. 3, 2017, the disclosures ofwhich are herein incorporated by reference in their entirety.

BACKGROUND 1. Field

The present invention generally relates to wireless communication andmore particularly, to a method and system for handling control planedata in a wireless network.

2. Description of Related Art

To meet the demand for wireless data traffic having increased sincedeployment of 4G communication systems, efforts have been made todevelop an improved 5G or pre-5G communication system. Therefore, the 5Gor pre-5G communication system is also called a ‘Beyond 4G Network’ or a‘Post LTE System’. The 5G communication system is considered to beimplemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, soas to accomplish higher data rates. To decrease propagation loss of theradio waves and increase the transmission distance, the beamforming,massive multiple-input multiple-output (MIMO), Full Dimensional MIMO(FD-MIMO), array antenna, an analog beam forming, large scale antennatechniques are discussed in 5G communication systems. In addition, in 5Gcommunication systems, development for system network improvement isunder way based on advanced small cells, cloud Radio Access Networks(RANs), ultra-dense networks, device-to-device (D2D) communication,wireless backhaul, moving network, cooperative communication,Coordinated Multi-Points (CoMP), reception-end interference cancellationand the like. In the 5G system, Hybrid FSK and QAM Modulation (FQAM) andsliding window superposition coding (SWSC) as an advanced codingmodulation (ACM), and filter bank multi carrier (FBMC), non-orthogonalmultiple access (NOMA), and sparse code multiple access (SCMA) as anadvanced access technology have been developed.

The Internet, which is a human centered connectivity network wherehumans generate and consume information, is now evolving to the Internetof Things (IoT) where distributed entities, such as things, exchange andprocess information without human intervention. The Internet ofEverything (IoE), which is a combination of the IoT technology and theBig Data processing technology through connection with a cloud server,has emerged. As technology elements, such as “sensing technology”,“wired/wireless communication and network infrastructure”, “serviceinterface technology”, and “Security technology” have been demanded forIoT implementation, a sensor network, a Machine-to-Machine (M2M)communication, Machine Type Communication (MTC), and so forth have beenrecently researched. Such an IoT environment may provide intelligentInternet technology services that create a new value to human life bycollecting and analyzing data generated among connected things. IoT maybe applied to a variety of fields including smart home, smart building,smart city, smart car or connected cars, smart grid, health care, smartappliances and advanced medical services through convergence andcombination between existing Information Technology (IT) and variousindustrial applications.

In line with this, various attempts have been made to apply 5Gcommunication systems to IoT networks. For example, technologies such asa sensor network, Machine Type Communication (MTC), andMachine-to-Machine (M2M) communication may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud RadioAccess Network (RAN) as the above-described Big Data processingtechnology may also be considered to be as an example of convergencebetween the 5G technology and the IoT technology.

As part of Control Plane Cellular Internet of Things (CP CIOT)optimization, the serving rate Public Land Mobile Network (PLMN) and APNrate control has been introduced to protect its Mobility ManagementEntity (MME). And also the signaling radio bearers in the EvolvedUniversal Terrestrial Radio Access Network (E-UTRAN) from load generatedby Non-Access-Stratum (NAS) messages with user data over control plane.The User Equipment (UE) should be able to send exception reports even incase the rate control limit has been reached.

The UE sends control plane data using ESM data transport messagepiggybacked on control plane service request message to core networkmobility management entity (MME). If MME is congested for control plane(CP) data then the MME accepts the received ESM data transport message,forwards the same to Service Capability Exposure Function (SCEF) or PDNGW and MME sends CP data back-off (BO) timer to UE along with a serviceaccept message if UE had indicated the support of CP Data BO timer. UEstarts CP back-off timer and does not send subsequent data over controlplane until CP BO timer is running. The issue with this prior artprocedure is that whenever MME receives the control plane data it isalways forced to accept and process it even though MME is congested.Further the accepted CP Data can add on to more processing when it getsforwarded to destination by MME. The destination may generateacknowledgement packet on reception of CP Data and due to this MME isagain forced to process this extra acknowledgement packet undercongestion situation. This forced processing of data on MME creates anextra load and will start using the resources secured for any criticalpurposes like emergency services or exception data.

If UE is running Control Plane data back off timer that means networkhad indicated to UE that its congested on control plane data path and UEis not expected to send the CP Data till CP Data BO timer is running.Meanwhile MME also runs the same timer for that particular UE(subscriber), so that next time if UE sends any request then MME canreject it by including the CPBO timer. However when UE sends the nextrequest if MME congestion is alleviated then how UE is synchronized withnew congestion alleviated situation at MME is not defined currently.

If the User Equipment (UE) is attempting to send exception data, then UEwill not be able to send the exception data to the network due tovarious reasons such as network congestion, UE abnormality. If the UEhas received indications from the network that its Packet Switched (PS)domain or control plane path is congested, then UE will not be able tosend the exception data to the network, as the PS domain back-off timeror CP back off timer will be running.

The UE initiates TAU or service request and if the MME is overloaded itmay reject the TAU request or service request from the UE with back-offtimer. Currently, the UE shall not initiate any NAS signaling or data tothe MME for the duration of the MM back-off timer. Hence resourcescannot be requested to network to send exception reports which are ofcritical nature.

SUMMARY

Whenever UE wants to send NAS signaling for exception data in IDLE modeit will set the RRC establishment cause to mo-exception data andestablish RRC connection. With this information network will prioritizethe exception data packet and will process even if network is incongested state and APN or SPLMN Rate control value is reached. Howeverif UE is already in connected mode and had established RRC connectionnot due to exception data and now if an exception data packet is sentover control plane or user plane then there is a risk of network(SCEF/MME/PDN GW) dropping that packet as network has no knowledge thatit's an exception data. Thus 3GPP system will end up dropping thecritical exception data and can have serious consequences to the user.

Thus, there is a need for a method of handling control plane dataespecially exception data that is critical in a wireless network.

The various embodiments of the present invention disclose a method ofhandling control plane data in a wireless network. According to anembodiment of the present invention, a method comprises sending, by auser entity (UE), a non-access stratum (NAS) message along with anindication data to a mobility management (MM) core network entity. TheMM core network entity processes the received NAS message and theindication data. The MM core network entity determines status of networkcongestion upon processing the processed NAS message. Sending, by the MMcore network entity, a response to the UE based on at least one of theprocessed indication data and the determined network congestion.

According to an embodiment of the present invention, the currentinvention utilizes the indication provided by UE in Release assistanceIndication IE as part of ESM Data Transport message to MME. 3GPPspecification has defined release assistance indication informationelements (IE) in ESM data transport message. Here EPS is evolved packetsystem. As per the Rel-14 of 3GPP specification the Release assistanceindication IE is defined to include only 2 values by UE: One of thevalues for Release assistance indication value is 2 i.e. “only a singledownlink data transmission (e.g. acknowledgement or response to uplinkdata) and no further uplink data transmission subsequent to the uplinkdata transmission is expected”. This indicates to MME that if it acceptsthe incoming CP Data packet then there will also be one moreacknowledgement packet it will have to process so till the duration ofone more downlink packet (e.g. acknowledgement) MME is expected to notrelease the resources (RRC Connection) even in the congestion situation.Thus MME can decide to reject the request by providing SERVICE Rejectmessage to UE along with CPBO timer. When Service Reject is receivedthis identifies to UE that sent uplink data packet is not successfullytransferred and if required UE will have to retransfer it and it cannotsend any more CP Data packets till received CPBO timer expires.

If value 2 is not set in RAI then other value possible is “1”. i.e. “nofurther uplink or downlink data transmission is expected” whichindicates to MME that this is last packet UE wants to send and afterthis MME can release the resources (RRC connection) for the UE. As datapacket is already reached till MME and its last packet to be processedMME will decide to process this packet and send Service Accept to UEalong with CP Back off timer. When UE receives Service Accept message UEidentifies that sent CP Data packet is successfully transferred but MMEis congested and thus UE will not send any more CP Data packets infuture till CP Data BO timer is running.

According to an embodiment of the present invention, if UE sends any NASmessage like control plane service request (due to paging or mosignaling or mo data or SMS etc.) or TAU while CPBO timer is running onUE side which also means that there will be CPBO timer running on MMEside for the same UE. If MME control plane data congestion situation isalleviated and decides to accept NAS message then MME shall providecorresponding NAS Accept message (like Service Accept or TAU Accept)without including CPBO timer IE to UE. Now as CPBO timer IE is notincluded UE shall stop the running CPBO timer on its sides. This is howcongestion alleviated situation at MME can be synchronized with UE.

According to an embodiment of the present invention, the method furthercomprises identifying a first control plane (CP) back-off timer is inrunning state. The UE sends the NAS message to the MM core networkentity during the running state of the first CP back-off timer. The MMEthen processes the received NAS message. Sending by the MM core networkentity, one of an acceptance message and reject message for theprocessed NAS message along with a second CP back-off timer to the UE incase of network congestion. The UE stops the first CP back-off timerupon receipt of the second CP back-off time. The second CP back-offtimer is started at the UE once the first CP back-off timer is stopped.

According to an embodiment of the present invention, the method furthercomprises identifying, by the UE a back-off timer is in running state.Receiving by the UE, an information about occurrence of an exceptionalevent during the running state of the first back-off timer. The UEattempts to send the NAS message to the MM core network entity uponreceiving the information about occurrence of an exceptional event evenif the back-off timer is in running state.

According to an embodiment of the present invention, If UE is trying tosend exception data i.e. RRC establishment cause was set to mo-exceptiondata then in general congestion situation network is expected to processand accept such data but if network is too much congested and not in asituation to process even exception data then to protect network,network can provide a back-off timer to UE. Under such situation ifback-off timer is received by UE then UE shall not try to send evenexception data till the latest received CPBO timer is running. i.e, UEwhenever it has exception data to be sent it checks if back off timer isrunning and if the back-off timer was not received from network when RRCestablishment cause was set to mo-exception data only then it is allowedto initiate NAS signaling for exception data.

According to an embodiment of the present invention, the method furthercomprises identifying, by the UE, a control plane back-off timer is inrunning state. The UE attempts to stop the control plane back-off timerupon occurring of one of the UE entering EMM_DEREGISTERED state and UEperforming PLMN change except EPLMN.

According to an embodiment of the present invention, the method furthercomprises identifying, by the UE, a back-off timer is in running stateand UE had not started the first back-off timer when a NAS message wassent due to an exception event and in response network provided theback-off timer. Receiving by the UE, an information about occurrence ofan exceptional event during the running state of the first back-offtimer. The UE attempts to send one of the NAS message to the MM corenetwork entity upon receiving the information about occurrence of anexceptional event even if the back-off timer is in running state. The MMcore network entity processes the received NAS message. Sending, by theMM core network entity, an acceptance for the processed NAS messagewithout including a back-off timer, to the UE as the request is due toan exceptional event. The running state of the CP back-off timer ismanaged at the UE in the absence of second CP back-off timer.

According to an embodiment of the present invention, the method furthercomprises sending, by UE, the NAS message with an indication that thecontrol plane data is related to an exceptional event as part of packetheader in the NAS message. Processing, by the MM core network entity,the received NAS message to identify that the data packet is related toexceptional event, said data is accepted and a priority treatment isprovided even if network is congested or access point name (APN) ratecontrol limit has reached or Serving PLMN Rate control limit hasreached. Processing, by a packet gateway (PGW), the received datapackets to identify that the data packet is related to exceptionalevent, said data is accepted and a priority treatment is provided evenif PGW is congested or APN or Serving PLMN rate control limit hasreached.

According to an embodiment of the present invention, the method furthercomprises identifying, by the UE, that UE is in one of an attempting toupdate state or attempting to attach state during one of running timerT3402 and timer T3411. Receiving by the UE, an information aboutoccurrence of an exceptional event. Attempting by the UE, to send one ofthe ATTACH message and TAU message to the MM core network entity uponreceiving the information about occurrence of an exceptional event.

According to an embodiment of the present invention, the NAS messagecomprises at least one of an attach request message, TAU requestmessage, Control Plane (CP) Service Request message and Service requestmessage. The exception event occurs comprises UE is allowed to sendexception data as per UE and network configuration and UE wants to senda critical data for which the UE sets radio resource control (RRC)Establishment cause to mo-exception data to get priority in networkside. The back-off timer comprises at least one of mobility management(MM) back-off timer, control plane (CP) data congestion back-off timer,and APN congestion back-off timer.

According to an embodiment of the present invention, it is possible toprovide a method for handling control plane data especially exceptiondata that is critical in a wireless network.

BRIEF DESCRIPTION OF THE DRAWINGS

The other objects, features and advantages will occur to those skilledin the art from the following description of the preferred embodimentand the accompanying drawings in which:

FIG. 1 is a schematic flow diagram illustrating transfer of controlplane data using ESM data transport message, according to the prior artillustration.

FIG. 2 is a schematic flow diagram illustrating transfer of small datausing ESM data transport message where release assistance indication IEis set to 01, according to an embodiment of the present invention.

FIG. 3 is a schematic flow diagram illustrating transfer of controlplane data using ESM data transport message where release assistanceindication IE is set to 02, according to an embodiment of the presentinvention.

FIG. 4 is a schematic flow diagram illustrating transfer ofattach/TAU/Service Request/Control Plane Service Request message betweenUE and MME, according to the prior art illustration.

FIG. 5 is a schematic flow diagram illustrating dynamic handling of CPBO timer, according to an embodiment of the present invention.

FIG. 6 is a schematic flow diagram illustrating stopping of the CP BOtimer value running on UE by network, according to an embodiment of thepresent invention.

FIGS. 7A and 7B are schematic flow diagrams illustrating exception datato be sent even when MM back off timer is running or UE has faced anabnormal situation, according to an embodiment of the present invention.

FIG. 8 is a schematic flow diagram illustrating that handling ofexception data during network congestion situation, according to anembodiment of the present invention.

FIG. 9 is a schematic flow diagram illustrating transfer of exceptiondata when UE faces abnormality, according to an embodiment of thepresent invention.

FIG. 10 is a schematic flow diagram illustrating transfer of exceptiondata when UE is EMM is in connected mode, according to the prior artillustration.

FIG. 11 is a schematic flow diagram illustrating transfer of exceptiondata when UE is EMM is in connected mode, according to an embodiment ofthe present invention.

Although specific features of the present invention are shown in somedrawings and not in others. This is done for convenience only as eachfeature may be combined with any or all of the other features inaccordance with the present invention.

DETAILED DESCRIPTION

The present invention claims benefit of the Indian ProvisionalApplication No. 201641023071 titled “A METHOD AND SYSTEM FOR PROVIDINGCELLULAR INTERNET OF THINGS (CIOT) OPTIMIZATION IN 3RD GENERATIONPARTNERSHIP PROJECT TECHNICAL SPECIFICATION (3GPP TS)” by SamsungElectronics CO., LTD, filed on 5 Jul. 2016 and Indian ProvisionalApplication No. 201641028365 titled “SYSTEM AND METHOD FOR CELLULARINTERNET OF THINGS (CIOT) OPTIMIZATIONS” by Samsung Electronics CO.,LTD, filed on 19 Aug. 2016 and Indian Provisional Application No.201641033734 titled “OPTIMIZATION FOR HANDLING NB-IOT DEVICES” bySamsung Electronics CO., LTD, filed on 3 Oct. 2016, which is hereinincorporated in its entirety by reference for all purposes.

The foregoing has outlined, in general, the various aspects of theinvention and is to serve as an aid to better understanding the morecomplete detailed description which is to follow. In reference to such,there is to be a clear understanding that the present invention is notlimited to the method or application of use described and illustratedherein. It is intended that any other advantages and objects of thepresent invention that become apparent or obvious from the detaileddescription or illustrations contained herein are within the scope ofthe present invention.

The various embodiments of the present invention disclose a method ofhandling control plane data in a wireless network. In the followingdetailed description of the embodiments of the invention, reference ismade to the accompanying drawings that form a part hereof, and in whichare shown by way of illustration specific embodiments in which theinvention may be practiced. These embodiments are described insufficient detail to enable those skilled in the art to practice theinvention, and it is to be understood that other embodiments may beutilized and that changes may be made without departing from the scopeof the present invention. The following detailed description is,therefore, not to be taken in a limiting sense, and the scope of thepresent invention is defined only by the appended claims.

The specification may refer to “an”, “one” or “some” embodiment(s) inseveral locations. This does not necessarily imply that each suchreference is to the same embodiment(s), or that the feature only appliesto a single embodiment. Single features of different embodiments mayalso be combined to provide other embodiments.

As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless expressly stated otherwise. Itwill be further understood that the terms “includes”, “comprises”,“including” and/or “comprising” when used in this specification, specifythe presence of stated features, integers, steps, operations, elementsand/or components, but do not preclude the presence or addition of oneor more other features integers, steps, operations, elements,components, and/or groups thereof. As used herein, the term “and/or”includes any and all combinations and arrangements of one or more of theassociated listed items.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure pertains. It willbe further understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

The present invention provides a method of handling control plane datain a wireless network. The person having ordinarily skilled in the artcan understand that the described embodiments use cases are for betterunderstanding and illustration of the present invention, but not limitto scope of the present invention.

FIG. 1 is a schematic flow diagram illustrating transfer of controlplane data using ESM data transport message, according to the prior artillustration. According to FIG. 1, user equipment (UE) 101 sends smalldata using ESM data transport message on control plane service requestmessage to mobility management entity (MME) 102. MME is the core networkmobility management entity. If MME 102 is congested for control plane(CP) data then the MME accepts the received control plane data andforwards the same to SCEF 103. MME 102 processes the data and due tocontrol plane path congestion, MME 102 sends CP data back-off (BO) timerto UE 101 along with a service accept message. UE 101 starts CP back-offtimer and does not send any data over control plane until CP BO timer isrunning.

FIG. 2 is a schematic flow diagram illustrating transfer of small datausing ESM data transport message where release assistance indication IEis set to 01, according to an embodiment of the present invention. 3GPPspecification has defined release assistance indication informationelements (IE) in EPS session management (ESM) data transport message.Here EPS is evolved packet system. According to an embodiment of thepresent invention MME checks for IE in ESM Data Transport message. Asper the Rel-14 of 3GPP specification the Release assistance indicationIE is defined to be including only 2 values. Where Release assistanceindication IE is set to 01 indicates that there is no further uplink ordownlink data transmission is expected for the sent uplink data,according to an embodiment of the present invention. According to FIG.2, UE 201 indicates in a release assistance indication IE in theNon-Access-Stratum (NAS) PDU that no further uplink or downlink datatransmissions are expected. According to an embodiment of the presentinvention, the Release assistance indication IE value is set at 01. UE201 sends the control plane service request with IE set at 01 in ESMdata transport message to MME 202. MME 202 processes the receivedcontrol plane data packet. After processing, MME 202 sends serviceaccept message with control plane back-off timer to UE 201. On receivingservice accept message, the UE 201 interprets this as successfultransmission of the control plane data packet. UE 201 then starts thecontrol plane back-off timer.

FIG. 3 is a schematic flow diagram illustrating transfer of controlplane data using ESM data transport message where release assistanceindication IE is set to 02, according to an embodiment of the presentinvention. If IE is set to 02 it indicates that there is only a singledownlink data transmission (e.g. acknowledgement or response to uplinkdata) and no further uplink data transmission subsequent to the uplinkdata transmission is expected. According to FIG. 3, UE 301 indicates ina release assistance indication IE that UE 301 expects downlink dataafter sending control plane service request. According to an embodimentof the present invention, the IE value is set at 02. UE 301 sends thecontrol plane service request with IE set at 02 in ESM data transportmessage to MME 302. However, MME 302 is overloaded and the servicerequest is rejected. MME 302 decides not to process the received controlplane data packet and sends service reject message with control planeback-off timer to UE 301. On receiving service reject message, the UE301 interprets this as unsuccessful transmission of the control planedata packet. UE 301 then starts the control plane back-off timer.

According to an embodiment of the present invention, based on releaseassistance indication (RAI) IE value in ESM data transport message,network determines whether to accept the CP data or reject it. In caseRAI is 1 then service accept is sent to UE and indicates to UE that MMEhas successfully processed the CP data however control plane (CP)back-off (BO) timer is provided so that UE shall not again initiate CPdata till CP BO timer expires. In case RAI is 2 then service reject issent to UE and indicates to UE that MME is congested for CP data andsent data packet is not processed successfully by network. Further CP BOtimer is provided so that UE shall not again initiate CP data till CP BOtimer expires.

FIG. 4 is a schematic flow diagram illustrating transfer ofattach/TAU/Service Request/Control Plane Service Request message betweenUE and MME, according to the prior art illustration. According to FIG.4, UE 401 has received control plane back-off timer in service acceptmessage and CP back-off timer is running. UE 401 triggers NAS messagesuch as Attach/TAU request/CP service request message and is sent to MME402. MME 402 then sends Attach/TAU accept/Service accept message to UE401. The CP back-off timer keeps on running in UE 401 and there is noimpact on the CP back-off timer state due to network signaling. Thenetwork is unable to change control plane back-off timer value which isrunning in UE 401 and also cannot indicate its congestion alleviatedsituation if there is no MT data packet.

FIG. 5 is a schematic flow diagram illustrating dynamic handling of CPBO timer, according to an embodiment of the present invention. Accordingto FIG. 5, dynamic handling of control plane (CP) back-off (BO) timer isillustrated. According to an embodiment of the present invention, UE 501has received control plane back-off timer in service accept message andCP back-off timer is running. UE 501 triggers Attach/TAU/Service requestmessage and is sent to MME 502. MME 502 then sends a new timer value inAttach/TAU accept/Service Accept/Service Reject message to UE 501. Onreceiving the new timer value UE 501 shall stop the CP back-off timerthat is running and restart the timer again with new value received fromthe network.

FIG. 6 is a schematic flow diagram illustrating stopping of the CP BOtimer value running on UE by network, according to an embodiment of thepresent invention. According to FIG. 6, stopping of the CP BO timervalue running on UE by network is illustrated. According to anembodiment of the present invention, UE 601 has received control planeback-off timer in service accept message and CP back-off timer isrunning. UE 601 triggers Attach/TAU/CP Service request message and issent to MME 602. MME 602 then sends Attach/TAU/Service Accept message toUE 601 without including CP BO timer value IE. After which UE 601 stopsthe running timer as the timer value IE is not received from thenetwork.

FIGS. 7A and 7B are schematic flow diagrams illustrating exception datato be sent even when MM back off timer is running or UE has faced anabnormal situation, according to an embodiment of the present invention.According to an embodiment of the present invention, exception data issent by UE even when MM back off timer is running. An applicationprocessor (AP) requests for an exceptional event, the communicationprocessor (CP) in UE then initiates TAU or Attach procedure if it's inNOT UPDATED (Attempting to UPDATE or Attempting to Attach etc.) stateeven if timer is running (as shown FIG. 7A). In another embodiment ofthe present invention, the application processor (AP) requests for anexceptional event, the communication processor (CP) in UE then initiatescontrol plane service request procedure if it's in UPDATED stateirrespective of whether timer is running (as shown FIG. 7B).

FIG. 8 is a schematic flow diagram illustrating that handling ofexception data during network congestion situation, according to anembodiment of the present invention. According to FIG. 8, theapplication processor (AP) 801 in UE requests to send exception data.The communication processor (CP) 801 in UE sends NAS message to MME 802with RRC establishment cause not set to mo-exception data. MME 802 sendscorresponding NAS reject with back-off timer to UE 801. The UE 801 willnot be allowed to send data or signaling as long as back-off timer isrunning. Here back-off timer is started when RRC Establishment cause wasnot set to mo-exception data. If exception data is generated, eventhough back-off timer is running exception data could be sent. The UE801 again sends NAS message to MME 802 with RRC establishment cause setto mo-exception data. MME 802 sends corresponding NAS reject withback-off timer to UE 801. The UE 801 will not be allowed to send evenexception data as long as back-off timer is running.

FIG. 9 is a schematic flow diagram illustrating transfer of exceptiondata when UE faces abnormality, according to an embodiment of thepresent invention. According to the present invention, if UE 902 facesabnormality and gets into attempting to update state or attempting toattach state, then UE 902 should be allowed to initiate Attach or TAUprocedure to send exception data. The UE 902 shall initiate Attach orTAU procedure if it's in NOT UPDATED (Attempting to UPDATE or Attemptingto Attach etc.) state.

FIG. 10 is a schematic flow diagram illustrating transfer of exceptiondata when UE is EMM is in connected mode, according to the prior artillustration. According to FIG. 10, UE 1001 is in connected mode andsends ESM data transport message to network 1002. The network 1002 hasno information whether the received data PDU is normal data or exceptiondata. Therefore the network provides same treatment to any kind of datathat is being received. If APN rate control or SPLMN rate control limitis reached or network is congested, packet will be dropped.

FIG. 11 is a schematic flow diagram illustrating transfer of exceptiondata when UE is EMM is in connected mode, according to an embodiment ofthe present invention. According to FIG. 11, UE 1101 is in connectedmode and sends ESM data transport message along with an indication thatit is carrying exception data to network 1102. The network 1102 providespriority treatment to the exception data. The ESM data transport messageis processed by the network 1102 even though APN rate control or servingPLMN rate control limit is reached or network is congested.

The present embodiments have been described with reference to specificexample embodiments; it will be evident that various modifications andchanges may be made to these embodiments without departing from thebroader spirit and scope of the various embodiments. Furthermore, thevarious devices, modules, and the like described herein may be enabledand operated using hardware circuitry, for example, complementary metaloxide semiconductor based logic circuitry, firmware, software and/or anycombination of hardware, firmware, and/or software embodied in a machinereadable medium. For example, the various electrical structure andmethods may be embodied using transistors, logic gates, and electricalcircuits, such as application specific integrated circuit.

Although the embodiments herein are described with various specificembodiments, it will be obvious for a person skilled in the art topractice the invention with modifications. However, all suchmodifications are deemed to be within the scope of the claims. It isalso to be understood that the following claims are intended to coverall of the generic and specific features of the embodiments describedherein and all the statements of the scope of the embodiments which as amatter of language might be said to fall there between.

What is claimed is:
 1. A method performed by an entity for managingmobility of a terminal in a wireless communication system, the methodcomprising: receiving, from a terminal, a control plane service requestmessage with uplink data; and transmitting, to the terminal, a serviceaccept message, in case that a release assistance indication (RAI)included in the control plane service request message is set to nofurther transmission of uplink data and downlink data subsequent to thetransmission of the uplink data being expected, wherein a value of aback-off timer, associated with a congestion control for transport ofuser data via a control plane is not included in the service acceptmessage, in case that the entity for managing mobility of the terminalis not overloaded, and wherein the back-off timer run in the terminal isstopped, based on the service accept message without the value of theback-off timer.
 2. The method of claim 1, further comprising:determining the congestion control for the transport of the user datavia the control plane upon receipt of the control plane service requestmessage, in case that the entity for managing mobility of the terminalis overloaded, wherein the service accept message includes a first valueof the back-off timer, based on the congestion control for the transportof the user data via the control plane being determined, and wherein theback-off timer based on a second value which is run in the terminal isstopped and is started based on the first value.
 3. The method of claim2, wherein the service accept message is used for identifying thetransport of the user data via the control plane as successful.
 4. Themethod of claim 1, further comprising: transmitting, to the terminal, aservice reject message, in case that the RAI is not set to no furthertransmission of uplink data or downlink data subsequent to thetransmission of the uplink data being expected, wherein the value of theback-off timer is included in the service reject message.
 5. The methodof claim 4, wherein the service reject message is used for identifyingthe transport of the user data via the control plane as unsuccessful. 6.A method performed by a terminal in a wireless communication system, themethod comprising: transmitting, to an entity for managing mobility ofthe terminal, a control plane service request message with uplink data;receiving, from the entity for managing mobility of the terminal, aservice accept message, in case that a release assistance indication(RAI) included in the control plane service request message is set to nofurther transmission of uplink data and downlink data subsequent to thetransmission of the uplink data being expected; and stopping a back-offtimer, associated with a congestion control for transport of user datavia a control plane, run in the terminal is stopped, in case that theservice accept message does not include a value of the back-off timer,wherein the value of the back-off timer is not included in the serviceaccept message, in case that the entity for managing mobility of theterminal is not overloaded.
 7. The method of claim 6, stopping theback-off timer based on a first value which is run in the terminal, incase that a second value of the back-off timer is included in theservice accept message; and starting the back-off timer based on thesecond value, wherein the second value of the back-off timer is includedin the service accept message, in case that the congestion control forthe transport of the user data via the control plane is determined bythe entity for managing mobility of the terminal.
 8. The method of claim7, further comprising: identifying the transport of the user data viathe control plane as successful based on the service accept message. 9.The method of claim 6, further comprising: receiving, from the entityfor managing mobility of the terminal, a service reject message, in casethat the RAI is not set to no further transmission of uplink data ordownlink data subsequent to the transmission of the uplink data beingexpected, wherein a value of the back-off timer is included in theservice reject message.
 10. The method of claim 9, further comprising:identifying the transport of the user data via the control plane asunsuccessful based on the service reject message.
 11. An entity formanaging mobility of a terminal in a wireless communication system, theentity for managing mobility of the terminal comprising: a transceiver;and a controller configured to: control the transceiver to receive, froma terminal, a control plane service request message with uplink data;and control the transceiver to transmit, to the terminal, a serviceaccept message, in case that a release assistance indication (RAI)included in the control plane service request message is set to nofurther transmission of uplink data and downlink data subsequent to thetransmission of the uplink data being expected, wherein a value of aback-off timer, associated with a congestion control for transport ofuser data via a control plane is not included in the service acceptmessage, in case that the entity for managing mobility of the terminalis not overloaded, and wherein the back-off timer run in the terminal isstopped, based on the service accept message without the value of theback-off timer.
 12. The entity for managing mobility of the terminal ofclaim 11, wherein the controller is further configured to determine thecongestion control for the transport of the user data via the controlplane upon receipt of the control plane service request message, in casethat the entity for managing mobility of the terminal is overloaded,wherein the service accept message includes a first value of theback-off timer, based on the congestion control for the transport of theuser data via the control plane being determined, and wherein theback-off timer based on a second value which is run in the terminal isstopped and is started based on the first value.
 13. The entity formanaging mobility of the terminal of claim 12, wherein the serviceaccept message is used for identifying the transport of the user datavia the control plane as successful.
 14. The entity for managingmobility of the terminal of claim 11, wherein the controller is furtherconfigured to control the transceiver to transmit, to the terminal, aservice reject message, in case that the RAI is not set to no furthertransmission of uplink data or downlink data subsequent to thetransmission of the uplink data being expected, and wherein a value ofthe back-off timer is included in the service reject message.
 15. Theentity for managing mobility of the terminal of claim 14, wherein theservice reject message is used for identifying the transport of the userdata via the control plane as unsuccessful.
 16. A terminal in a wirelesscommunication system, the terminal comprising: a transceiver; and acontroller configured to: control the transceiver to transmit, to anentity for managing mobility of the terminal, a control plane servicerequest message with uplink data; control the transceiver to receive,from the entity for managing mobility of the terminal, a service acceptmessage, in case that a release assistance indication (RAI) included inthe control plane service request message is set to no furthertransmission of uplink data and downlink data subsequent to thetransmission of the uplink data being expected; and stop a back-offtimer, associated with a congestion control for transport of user datavia a control plane, run in the terminal is stopped, in case that theservice accept message does not include a value of the back-off timer,wherein the value of the back-off timer is not included in the serviceaccept message, in case that the entity for managing mobility of theterminal is not overloaded.
 17. The terminal of claim 16, wherein thecontroller is further configured to stop the back-off timer based on afirst value which is run in the terminal, in case that a second value ofthe back-off timer is included in the service accept message, and startthe back-off timer based on the second value, and wherein the secondvalue of the back-off timer is included in the service accept message,in case that the congestion control for the transport of the user datavia the control plane is determined by the entity for managing mobilityof the terminal.
 18. The terminal of claim 17, wherein the controller isfurther configured to identify the transport of the user data via thecontrol plane as successful based on the service accept message.
 19. Theterminal of claim 16, wherein the controller is further configured tocontrol the transceiver to receive, from the entity for managingmobility of the terminal, a service reject message, in case that the RAIis not set to no further transmission of uplink data or downlink datasubsequent to the transmission of the uplink data being expected, andwherein a value of the back-off timer is included in the service rejectmessage.
 20. The terminal of claim 19, wherein the controller is furtherconfigured to identify the transport of the user data via the controlplane as unsuccessful based on the service reject message.